Trends and facility-level factors associated with malaria diagnostic testing in six regions of differing endemicity, mainland Tanzania, 2021–2023

Universal parasitological testing of suspected malaria cases is a cornerstone of malaria control and elimination strategies. In Tanzania, routine surveillance data indicate that malaria testing coverage remains below national targets, despite widespread availability of malaria rapid diagnostic tests (mRDTs). Understanding trends and facility-level factors associated with malaria testing is essential to strengthen diagnostic practices, particularly across varying transmission settings. We conducted a repeated cross-sectional analysis of routine health facility data from six malaria-endemic regions of mainland Tanzania using the District Health Information System version 2 (DHIS2) and the electronic Logistics Management Information System (eLMIS). Data from January 2021 to December 2023 were included. The primary outcome was the malaria testing rate, defined as the proportion of outpatient department (OPD) attendees tested for malaria using mRDTs at each facility per year. Facility-level characteristics, malaria endemicity strata, implementing partner support, supportive supervision, and mRDT stock status were examined. Temporal trends were assessed using non-parametric tests, and associations were evaluated using multivariable linear regression models with robust standard errors. A total of 1,318 health facilities in 2021, 1,448 in 2022, and 1,553 in 2023 met data completeness criteria and were included in the analysis. Overall malaria testing rates declined significantly over the study period (β = −0.03; 95% CI −0.04 to −0.02). Facilities located in low- and very low-endemic strata consistently demonstrated lower malaria testing rates compared with those in high-endemic areas. Health centres had higher testing rates than dispensaries, while hospitals showed persistently lower testing performance. Although mRDT availability was generally adequate and overstocking increased over time, this did not translate into improved testing rates. Implementing partner support was positively associated with malaria testing in some years. Malaria diagnostic testing rates declined between 2021 and 2023 across six endemic regions of mainland Tanzania, despite adequate availability of mRDTs. Lower testing in hospitals and in low-transmission settings highlights persistent health system and behavioural barriers to malaria diagnosis. Strengthening facility-level adherence to testing guidelines, particularly in low-endemic areas and higher-level facilities, is critical to support malaria elimination efforts.